Beaconsfield is a market town in Buckinghamshire. It’s where the Whiteheads live, on Tilsworth Road. Robin goes here to interview Mr Whitehead in Chapter 102.

Robin is on surveillance of Plug but hands over to Midge and sets of for Beaconsfield. She arrives on Tilsworth Road shortly before seven o’clock.
“The Whiteheads’ house was large, made of red brick and had a double garage.” Robin drives the Land Rover a little up the road to a parking space outside a range of traffic lights.

She is greeted by Faber Whitehead and talks to him about Tyler Powell, a potential for William Wright.